Dr. Dimitrios Babas
'%3e%3cpath%20d='M22.1642%2019.0924C21.7317%2018.068%2021.1041%2017.1375%2020.3163%2016.3527C19.5309%2015.5656%2018.6006%2014.9381%2017.5766%2014.5048C17.5674%2014.5002%2017.5582%2014.4979%2017.5491%2014.4933C18.9774%2013.4616%2019.9059%2011.7811%2019.9059%209.88504C19.9059%206.74408%2017.3611%204.19922%2014.2201%204.19922C11.0792%204.19922%208.53429%206.74408%208.53429%209.88504C8.53429%2011.7811%209.46282%2013.4616%2010.8912%2014.4956C10.882%2014.5002%2010.8728%2014.5025%2010.8636%2014.5071C9.83652%2014.9404%208.91487%2015.5617%208.1239%2016.355C7.33685%2017.1404%206.70933%2018.0707%206.276%2019.0947C5.85031%2020.0972%205.62072%2021.172%205.59967%2022.2609C5.59905%2022.2853%205.60335%2022.3097%205.61229%2022.3325C5.62123%2022.3553%205.63465%2022.376%205.65174%2022.3935C5.66883%2022.4111%205.68926%2022.425%205.71182%2022.4345C5.73437%2022.444%205.7586%2022.4489%205.78308%2022.4489H7.15868C7.25956%2022.4489%207.3398%2022.3686%207.3421%2022.2701C7.38795%2020.5001%208.09868%2018.8425%209.35506%2017.5861C10.655%2016.2862%2012.3814%2015.5709%2014.2201%2015.5709C16.0588%2015.5709%2017.7852%2016.2862%2019.0852%2017.5861C20.3415%2018.8425%2021.0523%2020.5001%2021.0981%2022.2701C21.1004%2022.3709%2021.1807%2022.4489%2021.2815%2022.4489H22.6571C22.6816%2022.4489%2022.7058%2022.444%2022.7284%2022.4345C22.751%2022.425%2022.7714%2022.4111%2022.7885%2022.3935C22.8056%2022.376%2022.819%2022.3553%2022.8279%2022.3325C22.8369%2022.3097%2022.8412%2022.2853%2022.8406%2022.2609C22.8176%2021.165%2022.5907%2020.0989%2022.1642%2019.0924ZM14.2201%2013.8284C13.1678%2013.8284%2012.1773%2013.418%2011.4322%2012.6729C10.6871%2011.9278%2010.2767%2010.9374%2010.2767%209.88504C10.2767%208.83271%2010.6871%207.84227%2011.4322%207.09715C12.1773%206.35204%2013.1678%205.94165%2014.2201%205.94165C15.2724%205.94165%2016.2629%206.35204%2017.008%207.09715C17.7531%207.84227%2018.1635%208.83271%2018.1635%209.88504C18.1635%2010.9374%2017.7531%2011.9278%2017.008%2012.6729C16.2629%2013.418%2015.2724%2013.8284%2014.2201%2013.8284Z'%20fill='%238590A2'/%3e%3c/g%3e%3c/svg%3e)
Co-authors
Following
Followers
Research Focus & Metrics
Explore full metrics on Scilit
Academic Career Length
20Years (2007-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications1 November 2016 in IET Microwaves, Antennas & Propagation
Journal Article
TKTheodorοs N. Kaifas
Theodorοs N. Kaifas
Dimitrios BabasGTGiovanni Toso
Giovanni Toso
JSJohn Sahalos
John SahalosToday there is an increasing request for high‐throughput communication payloads in satellite communications. Capacity in the order of 100 Gbit/s is becoming available and further significant improvement is expected in the coming years. A key element in order to guarantee this high performance is constituted by the multibeam antennas, able to generate multiple narrowly focused spot beams with frequency and polarisation reuse. Direct radiating arrays are able to generate multibeam coverage with a single aperture with the possibility of reconfiguring the coverage and the power distribution among the beams. Sparse arrays permit to reduce the number of radiators and to increase the DC to RF power efficiency by exploiting a ‘space tapering’ instead of an ‘amplitude tapering’, typically adopted in periodic arrays to control the sidelobe level. In this study, a deterministic procedure for the design of large planar sparse arrays is extended to the case, where the antenna, from a geostationary satellite, has to generate a multibeam coverage on the full Earth. The synthesis procedure is presented and validated with several numerical examples illustrating the scanning losses, array pattern deformation during the scanning and grating lobe effects.
27 February 2007 in Electrical Engineering
Journal Article
Dimitrios BabasJSJohn Sahalos
John SahalosJournal Article
Spyridon DelidimitriouDimitrios BabasAMAthanasios Manassas
Athanasios Manassas
Joe Wiart
Theodoros SamarasThis study introduces a low-cost alternative method for mapping the electric field strength from 4G LTE base stations and identifies areas where this mapping is more accurate. A drive test campaign was conducted in the urban environment of Thessaloniki, Greece, using data obtained from three identical smartphones, each connected to a different mobile operator and an exposimeter. The smartphones used a mobile application to record Reference Signal Received Power (RSRP) values, while the exposimeter measured the electric field strength in selected frequency bands. In the first part, the variability of the received power over different periods within certain areas was studied, and the reasons for this variability were identified. In the second part, a linear factor was calculated to convert RSRP values into electric field strength using data from both the application and the exposimeter. The converted RSRP values were subsequently compared with the exposimeter data for validation. The results indicate that in areas where the variability of the received power is lower, the linear relationship between smartphone and exposimeter data is statistically stronger resulting in calculated electric field strength values are closer to the measured.
About Me
Dr. Dimitrios G. Babas received the B.Sc. degree in Physics in 1991 and the MSc in Electronic Physics (Radioelectrology) in 1995, both from the Aristotle University of Thessaloniki, (AUTH), Greece. He completed his PhD thesis on telecommunication waveguide systems (microstrip structures) at the Department of Physics of AUTH in 2001. He also received the Diploma of Postgraduate Studies in Telecommunication and Information Systems in 1992 from the University of Essex, UK.
Since 1992 he has been working as a research assistant at the Radio-Communications Laboratory (RCL), AUTh. During the period 1999-2008 he was a Scientific Associate in the Department of Electronics, Technological and Educational Institute of Thessaloniki, Greece. Since 2004 he has been a member of the teaching staff of the MSc in Electronic Physics (Radioelectronics), AUTh, and since 2014 he has been a member of the Laboratory Teaching Staff of the Department of Physics, AUTh. In 2011-13 he was a member of the Annual Board of Electromagnetic Compatibility Experts of the Ministry of Transport and Communications (Greece).
His research interests include waveguide systems, antenna systems design, wireless communications, satellite communications and RF measurements.
Dr. Babas is a member of IEEE.